JP2505376B2 - Film forming method and apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming method and apparatus, and more particularly to a film forming method and apparatus including an ultrafine particle film applicable to various compounds as film materials, not limited to metal and nonmetal.

[0002]

2. Description of the Related Art Conventionally, for producing ultrafine particles by an arc, a gas containing hydrogen is used as disclosed in Japanese Patent Publication No. 57-44725, and this gas is dissolved in a molten metal and convected. , Using the mechanism of release.

Further, as a method for forming a film of the ultrafine particles thus obtained, there are known a method of applying by dissolving in a solvent and a method of spraying by using a gas flow (JP-A-57-57).
196085).

[0004]

In the above-mentioned conventional ultrafine particle production, no consideration is given to production efficiency. Further, the above-mentioned conventional film forming methods have respective drawbacks that it is difficult to obtain a high-purity film in the former case and the apparatus becomes complicated in the latter case.

An object of the present invention is to provide a film forming method and a film forming apparatus for forming a high purity film efficiently and easily.

[0006]

When the laser energy is applied to the surface of the raw material, it takes various molten forms depending on its energy density. The present inventor has discovered that when the raw material is pulse-irradiated with a laser energy under a condition where a plume phenomenon occurs, that is, in a low vacuum atmosphere, a large amount of ultrafine particles are generated at a high speed. By irradiating the substrate surface with this plume, we succeeded in forming a simple and high-purity ultrafine particle film on the substrate surface.

The present invention is based on this discovery,
It is characterized in that a film is formed by irradiating the surface of the raw material with laser energy under a condition where a plume is generated in a predetermined atmosphere and directly applying the generated plume to the substrate.

That is, the raw material containing the constituent material of the film is pulse-irradiated under reduced pressure with a laser beam to generate a plume containing the constituent material of the film, and the plume is brought into direct contact with the object to be film-formed. When forming a film on the surface, the focal position of the laser light is adjusted and the plume properties (for example,
It is characterized in that the film is formed by adjusting the mixing ratio of atoms, molecules, clusters, ions, etc.).

An apparatus for carrying out this film-forming method comprises a film-forming chamber, a raw material containing the constituent substances of a film installed inside the film-forming chamber, and laser irradiation for irradiating the surface of the raw material with laser light in a pulsed manner. Means, a film forming object arranged at a position at least in contact with a plume formed on a surface of the raw material irradiated with laser light, an exhaust means for reducing the internal pressure of the film forming chamber, and a surface of the raw material And a laser energy adjusting means for adjusting the energy density of the laser beam applied to the laser under the condition that the plume is generated.

In this case, it is desirable to heat the film-forming target in advance. The heating means preferably uses energy other than laser light.

Examples of the predetermined atmospheric conditions include atmospheric pressure and atmospheric gas, as well as laser-irradiated material which is a raw material of ultrafine particles. Atmospheric pressure is 1.3 × 10 ^{4 to} 5 × 10
^By appropriately selecting from the range of ⁵ Pa, it is possible to form ultrafine particles with a predetermined particle size distribution. By appropriately selecting the atmospheric gas, it is possible to obtain a desired compound or alloy film by the reaction of this gas component with the plume and / or the film forming process or the film-formed product.

The raw material of the ultrafine particles is not particularly limited, and it is possible to form a desired metal, alloy or non-metal film by appropriately selecting it. Further, it is possible to form a mixed film of a metal and a compound by appropriately selecting both the alloy material and the atmospheric gas.

The present invention can also be used for a superconducting thin film having ultrafine particles. In this case, as a raw material, a sintered body of an oxide superconductor or a corresponding alloy, or a ceramic or an alloy having an element ratio different from that of the film formation to obtain a desired film formation composition is suitable. In this film formation, it is preferable to rapidly cool or gradually cool the film, and a heater or a high frequency induction coil can be used as the heating source. Many are slowly cooled (eg 2
00 ° C./hr) is more effective. In this case, examples of the substrate include an Al ₂ O ₃ substrate, a MgO substrate, a SrTiO ₃ single crystal substrate, and a Si substrate.

The present invention includes not only activating the surface of the raw material with laser energy, but also adding arc energy or discharge energy to this to further improve the production efficiency.

[0015]

When the raw material is irradiated with the laser energy density under the condition that the plume phenomenon occurs, a large amount of ultrafine particles are generated at a high speed by adjusting the focal position of the laser light. Since the plume containing a large amount of ultrafine particles (for example, metal vapor) migrates at a high speed, when it is applied to the substrate of the film formation target, it strongly adheres to this substrate to form a film. If the substrate is preheated, this adhesion will be even greater. Further, by adjusting the focal position of the laser light, the laser energy density on the surface of the raw material can be adjusted, and the film formation rate can be adjusted.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. (Laser Irradiation) FIG. 1 is an example of the configuration of a film forming apparatus that irradiates a laser beam on a surface of a raw material under conditions where a plume is generated and deposits the generated plume on the surface of a substrate. A YAG laser was used as the laser source 1 in this embodiment. The generated laser beam 2 enters the ultrafine particle deposition chamber 5 through the glass plate 4 while being converged by the condenser lens 3. The laser light 2 is applied to the raw material 6 located near the center of the bottom of the ultrafine particle deposition chamber 5. The condenser lens 3 is for condensing the laser light 2 from the laser source 1, and the distance from the focus is such that the condenser lens 3 side is negative and the raw material 6 side is positive with respect to the focal position 7.

(Generation of Plume) When the laser energy E (Joule / Pulse) applied to the surface of the raw material 6 is large, a large amount of spatter is generated. On the other hand, when the energy is small, a small amount of metal evaporates. It is difficult to observe clearly. Plume 8 containing a large amount of ultrafine particles can be recognized if proper energy is applied.

The plume refers to what is observed as shown by reference numeral 8 in FIG. 1 when the surface of the raw material is irradiated with laser energy or the like and a high-density vapor of a metal or the like, which is partially ionized, shines from the surface.

The relationship between the laser energy that gives the conditions for generating the plume 8 and the distance fd from the focus to the surface of the raw material is as shown in FIG. 2, where A is a region accompanied by sputtering, B is a region only with a plume, and C is a region. It is an area without plumes.
This relationship changes depending on the type of raw material 6, the surface state, the type of atmospheric gas, and the atmospheric pressure. In this example, titanium (Ti) was used as the raw material 6, the atmospheric pressure P in the ultrafine particle deposition chamber 5 was set to 1 atm, and the pulse time (τ) of the laser light 2 was set to 3.6 ms. The focal length f of the condenser lens 3 was 127 mm, and the atmosphere was air. As a result of examining various raw materials for the production of this plume,
Laser energy applied to the surface of raw material is 10 ⁴ to 10 ⁷ W /
It was found to be in the cm ² range.

As shown by the curve A in FIG. 3, the generation of the plume 8 requires a time of 0.05 to 0.3 ms after the irradiation of the laser energy E, and after a slight time delay, the evaporation starts and the high-speed steam is generated. Shift as a flow. This time (occurrence start time)
Varies depending on the degree of irradiation energy, that is, the distance fd from the focus. Further, the growth rate Vυ of the tip of the generated plume 8 greatly changes depending on the irradiation energy E and the atmospheric pressure P as shown by the curve B in FIG. 3 and FIG. The irradiation energy E and the atmospheric pressure P affect the production amount of ultrafine particles, the particle size, and the like.

The symbol ab in the figure represents [distance between lens 3 and raw material 6] / [focal length f of lens 3]. Incidentally, with respect to FIG. 3, the irradiation energy E is 36.5 J / P.
Other conditions were the same as those in FIG. In FIG. 4, τ was 3.6 ms, the atmosphere was air, and E, fd, and ab were the conditions shown in the figure.

FIG. 5 illustrates a state in which the plume 8 is moving as a high-speed steam flow. The plume 8 made of this metal vapor will condense vaporized atoms in the space during transfer to form ultrafine particles.

The transition speed of the plume tip is the inclination (υ
= Tan θ), and in this case ν = 15 m / s.
The transfer speed varies depending on the laser light irradiation conditions, raw materials, atmospheric pressure, etc., and examples are shown in Table 1.

[0024]

[Table 1]

The pulse time τ is 3.6 ms and the laser energy E is 36.5 J / P YAG. As shown in Table 1, graphite is the fastest. Therefore, by applying this plume to the substrate, it becomes possible to form a film of ultrafine particles.

(Production of Ultrafine Particles) A predetermined gas is introduced from the atmosphere gas supply pipe 9 into the ultrafine particle film forming chamber 5 in order to produce desired ultrafine particles. The opening portion of the supply pipe 9 has almost the same height as the raw material 6 near the bottom of the film forming chamber 5, and the supply gas flows out in the direction of the plume 8. A gate valve 10 is arranged on the supply pipe 9. Further, an exhaust pump 11 is installed on the opposite side to exhaust the inside of the film forming chamber 5, and the gate valve 10 is also arranged on this flow path. The atmospheric pressure is controlled by the exhaust pump 11, and the atmospheric gas exhausts the ultrafine particle deposition chamber 5 to a vacuum (about 10 to ³ torr),
After that, a predetermined gas is supplied to obtain the gas.

FIG. 6 illustrates the relationship between the irradiation energy E and the ultrafine particle production amount w. The energy region of the region A accompanied by the generation of spatter can be most efficiently generated by the energy irradiation of the region B which is slightly smaller. The conditions for this data were that nickel (Ni) was used as the raw material 6, the atmosphere gas was air, and the distance fd from the focus was 10 mm.

On the other hand, the amount W of production and the amount V of evaporation when various raw materials [titanium (Ti), iron (Fe), nickel (Ni), aluminum (Al), molybdenum (Mo)] are irradiated with constant energy are shown in FIG. 7 shows. The irradiation energy E is 2
2 J / P, atmosphere gas is argon, fd is 10 mm
And This relationship changes depending on the physical properties of the raw materials (surface absorption energy, thermal conductivity, evaporation temperature, melting temperature, etc.) as shown in the figure. The black line in the figure corresponds to the weight loss, that is, the production amount, and the white line corresponds to the evaporation amount. Therefore, the energy condition where the plume phenomenon is the most severe
Irradiation may be performed after grasping according to the surface condition, atmospheric gas, atmospheric pressure, laser type, laser light wavelength, optical system type, glass plate type, and the like.

As an example, regarding the relationship between the atmospheric pressure and the production amount when titanium (Ti) is used as the raw material, the production amount is the largest when the atmospheric pressure is 10 ⁵ Pa, which is close to the atmospheric pressure, as shown in FIG. Atmosphere gas is air, irradiation energy E is 3
3.4 J / P, pulse τ is 3.6 ms, fd is 24 mm, a
b was set to 1.189. From FIGS. 8 and 4, it can be seen that when the atmospheric pressure is 5 × 10 ⁵ Pa or less, the plume tip growth rate is high and the production amount is large.

As shown in FIG. 9, the intensity distribution of the ultrafine particles shows a particle size range of ^{5 to} 65 nm when the atmospheric pressure P = 10 ⁵ Pa. On the other hand, low atmospheric pressure 1.3 × 10 ⁴ Pa
In that case, the production amount is somewhat reduced, but fine (5 nm) ultrafine particles having a uniform particle size can be obtained. In addition, in FIG.
Is Ti, the atmosphere is air, E is 25 J / P, and τ is 3.6 m.
s and fd are +25 nm, and ab is 1.189.

FIG. 1 shows data obtained when iron (Fe) was used as the raw material and argon was used instead of air as the atmosphere.
0 is shown. It can be seen that the particle size becomes smaller (for example, 15 nm) and becomes more uniform as the pressure becomes lower regardless of the atmospheric gas. It is clear from FIGS. 9 and 10 that the particle size distribution of the ultrafine particle film can be controlled by the atmospheric pressure.

Ultrafine particles obtained by laser light irradiation can be used for most metal materials as shown in Table 2, and also for nonmetals and alloys. In the case of alloys, the composition of ultrafine particles tends to change somewhat.

Further, since the generated ultrafine particles are in a very active state, various ceramic ultrafine particles (compound ultrafine particles) can be produced by the direct chemical reaction between the plume and the atmospheric gas. Table 2 also shows an example of an oxide formed in an oxygen atmosphere and an example of a nitride formed in a nitrogen atmosphere pressure.

[0034]

[Table 2]

Further, by irradiating the alloy material with a laser beam in a reaction gas atmosphere, it is possible to generate mixed ultrafine particles of metal and ceramics. As an example, when the Fe—Ti alloy or Ni—Ti alloy is irradiated with laser light in a nitrogen atmosphere, mixed ultrafine particles of Fe and TiN in the former case and Ni and TiN in the latter case can be obtained. Also, laser energy and arc energy that can be used in combination with this,
Alternatively, as shown in FIG. 11, plasma is generated by the high frequency induction coil 15 and a part of the atmospheric gas is dissociated by the energy, so that N ₂ gas, O ₂ gas, methane (C
H ₄ ), acetylene (CH≡CH), freon (CCl ₂
It is possible to generate ultrafine carbide particles using a gas such as F ₂ ), propane (C ₃ H ₈ ), or butane (C ₄ H ₁₀ ). In addition to hydrocarbon-based gas, ammonia (NH ₃ )
Etc. can also be used. As described above, it is possible to generate compound ultrafine particles of a desired oxide, nitride or carbide by selecting a predetermined gas. Further, by directly irradiating these compounds (ceramics) with laser light, compound ultrafine particles can be similarly obtained. The energy used is YAG
In addition to the laser, other oscillation type lasers such as CO ₂ and die laser can be used.

(Film Forming Process) When the plume 8 is generated as described above, ultrafine particles are generated and the particles move upward at a high speed. Therefore, if the substrate 12 is placed at the transfer destination, that is, in the direction of the tip of the plume 8, the ultrafine particles will be formed thereon. Collide with each other to be deposited and an ultrafine particle film 13 can be formed.

The substrate 12 is preheated by the heater 14 in the example of FIG. 1, but as shown in FIG.
5 may be used. In addition to this, a light beam, a laser, or the like can be used as a heat source. In the figure, reference numeral 16 is a heater power source, reference numeral 17 is a matching unit, and reference numeral 18
Is a high frequency power supply.

As described above, since ultrafine particles are generated and migrate to the substrate at a high speed at the same time under the plume generation condition,
A high-purity ultrafine particle film can be easily obtained.

(Use for Forming Ceramics Superconducting Thin Film) The present invention can also be used for forming a powder or forming a film of a ceramic oxide superconducting material.

For example, the ultrafine particle film produced by irradiating the raw material 6 with the laser beam 2 has a predetermined composition of the superconducting material (for example, Y
Ba ₂ Cu ₃ O ₇ _ ₈ etc.) alloys (eg Y-B)
(a-Cu alloy) to generate a plume in an atmosphere of oxygen, oxygen and an inert gas, or oxygen or a fluoride gas to obtain an ultrafine particle film made of an oxide superconducting material on the substrate surface. . Alternatively, a plume may be generated in an inert atmosphere or an oxygen-containing atmosphere by using a sintered body of an oxide superconductor having the corresponding composition as a raw material.

Furthermore, the individual metal (Y, Ba, Cu, etc.) or compound (Y ₂ O ₃ , BaCO) constituting the final product is used.
It is also possible to obtain a predetermined superconducting material while irradiating laser energy to each of ( ₃ , CuO, etc.) for a predetermined time to generate a plume and to mix it during transfer to the substrate.

Incidentally, if the atmosphere is ionized by the high frequency induction coil 15 shown in FIG. 11, the reaction proceeds more effectively.

The film formed by the above method is heat-treated by heating the film in the high-frequency induction coil 15 in the deposition chamber 5 in an atmosphere of inert gas, oxygen, oxygen / inert gas, oxygen / fluoride gas, or the like ( For example, in the case of YBa ₂ Cu ₃ O ₇ _ ₈ superconducting material, by heating the raw material alloy in an oxygen atmosphere at 900 to 1050 ° C. for 5 hours and cooling it at 200 ° C./Hr), the high temperature superconducting material is brought online without being exposed to the atmosphere. It can be formed into a film.

The sintered body used as the raw material is, for example, a sintered body of calcined oxide superconductor powder. It is specifically created in example coprecipitation is obtained by sintering the _{Y 0. 4 Ba 0. 6} CuO 3 powder.

Further, for example, in order to obtain a La-Ba-Cu-O-based superconducting thin film, the corresponding oxide of each constituent metal element (carbon oxide for Ba) is used as a raw material, and it is formed in an argon atmosphere in consideration of irradiation time. Membrane is possible.

[0046]

According to the present invention, a plume generated by pulse-irradiating a raw material containing a constituent material of a film with a laser beam is directly applied to a film-forming surface to form a film. A film can be formed immediately. As a result, there is an effect that films of various materials can be easily obtained with high efficiency.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an ultrafine particle deposition apparatus to which an embodiment of the present invention is applied.

FIG. 2 is a relationship characteristic diagram between a focal length of a condenser lens and laser energy.

FIG. 3 is a relationship characteristic diagram of a focal length, a plume generation start time, and a plume tip growth rate.

FIG. 4 is a characteristic diagram showing the relationship between atmospheric pressure and plume tip growth rate.

FIG. 5 is a characteristic diagram illustrating a plume transition speed.

FIG. 6 is a characteristic diagram showing the relationship between laser energy and the amount of ultrafine particles produced.

FIG. 7 is a characteristic diagram showing the relationship between the production amount and the evaporation amount of ultrafine particles of various raw materials.

FIG. 8 is a relationship characteristic diagram between an atmospheric pressure and a production amount.

FIG. 9 is a characteristic diagram showing the influence of atmospheric pressure on the particle size.

FIG. 10 is a characteristic diagram showing the effect of atmospheric pressure on the particle size.

FIG. 11 is an enlarged schematic view of the vicinity of a substrate showing another embodiment.

[Explanation of symbols]

 1 Laser Source 2 Laser Light 3 Condensing Lens 4 Glass Plate 5 Ultra Fine Particle Filming Chamber 6 Raw Material 8 Plume 9 Atmospheric Gas Supply Pipe 11 Exhaust Pump 12 Substrate 13 Ultra Fine Particle Film 14 Heater 15 High Frequency Induction Coil

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C01G 1/00 C01G 1/00 S C23C 14/28 8939-4K C23C 14/28 (72) Inventor Mitsuaki Haneda 502 Jinrachi-cho, Tsuchiura-shi, Ibaraki Machinery Research Laboratory, Hitachi, Ltd. (72) Inventor Ryoji Okada 502, Jinmachi-cho, Tsuchiura-shi, Ibaraki Hitachi, Ltd., Mechanical Research Laboratory (56) References JP 60-194066 (JP, A) JP-A-53-39274 (JP, A)

Claims (16)

(57) [Claims] 1. A raw material containing a constituent material of a film is pulse-irradiated under reduced pressure with a laser beam to generate a plume containing the constituent material of the film, and the plume is brought into direct contact with an object to be film-formed. A film forming method, which comprises adjusting a focal position of the laser light to adjust a property of the plume in forming a film on the surface of the. 2. The film forming method according to claim 1, wherein the film is a superconducting film. 3. The film forming method according to claim 1, wherein the film is an oxide superconducting film. 4. The film forming method according to claim 1, further comprising ionizing an atmosphere gas. 5. The film forming method according to claim 1, wherein the film is formed by a reaction between a component of an atmospheric gas and the plume and / or a film forming process product or a film forming product. 6. The film forming method according to claim 1, wherein the laser energy density is 10 ^{4 to} 10 ⁷ W / cm ² . 7. The film forming method according to claim 1, wherein the film forming object is heated in advance. 8. The film forming method according to claim 1, wherein a film forming surface of the film forming object is arranged perpendicular to a growth direction of the plume. 9. The film forming method according to claim 1, wherein the plume contains a condensate of vaporized atoms of the raw material. 10. A film forming chamber, a raw material containing a constituent material of a film installed inside the film forming chamber, a laser irradiation unit for irradiating the surface of the raw material with a laser beam in a pulsed manner, and a laser beam of the raw material. Of the film formation target disposed at a position at least in contact with the plume formed on the surface irradiated with, the exhaust means for reducing the internal pressure of the film formation chamber, and the laser light irradiated on the surface of the raw material. A film forming apparatus comprising: a laser energy adjusting means for adjusting an energy density to a condition where the plume is generated. 11. The film forming apparatus according to claim 10, wherein the exhaust unit is capable of adjusting the internal pressure of the film forming chamber. 12. The film forming apparatus according to claim 10, further comprising ionizing means for ionizing an atmosphere gas in the film forming chamber, inside the film forming chamber. 13. The film forming apparatus according to claim 12, wherein the ionization unit is one of an arc energy generation unit and a high frequency induction coil. 14. The film forming apparatus according to claim 10, further comprising heating means for heating the film forming object in advance. 15. The film forming apparatus according to claim 14, wherein the heating means is one of a heater and a high frequency induction coil. 16. The film-forming surface of the film-forming target and the laser irradiation surface of the raw material are planes, and the film-forming surface and the laser irradiation surface are opposed to each other and arranged in parallel to each other. A film forming apparatus, which irradiates a laser beam while inclining it onto the laser irradiation surface.